Top Federal Aviation Administration officials said last night that they hope to be able to lift the ban on the ground Dc10 jumbo jet today or Tuesday.
Charles Foster, associate administrator for aviation standards and the chief technical adviser to FAA Administrator Langhorne M. Bond on the DC10 question, said in a telephone interview that the last of several technical issues has been resolved in a general way, but that details must be worked out. "It looks like it will be this week, we hope Monday or Tuesday," Foster said.
Foster outlined several changes in DC10 maintenance and equipment that the FAA will require, with emphasis on support pylons for the wing engines, on wing devices that give extra lift at takeoff, and on cockpit systems that are supposed to alert the crew to possible trouble.
Once those details -- in the form of specific instructions to the eight U.S. airlines that own 138 DC10s -- are resolved, the FAA will lift the ban on the planes, which have been grounded since June 6. The ban resulted from trouble found during inspections of all DC10s following the May 25 Chicago crash of American Airlines flight 191 in which 273 people were killed.
The FAA action won't mean the DC10s will begin flying immediately. First the FAA must inform U.S. District Court Judge Aubrey E. Robinson Jr. of its proposed actions 24 hours bore they are to take effect. Robinson is expected to hold a hearing, and at least one group, the Airline Passengers Association (APA), is expected to seek to keep the plane grounded.
The APA was successful earlier in obtaining a temporary injunction from Robinson that ordered the grounding of the DC10s.Although the FAA acted independently of that, there is little question that the order's existence put added pressure on Bond to ground the plane.
Bond, Foster and other senior FAA officials were in Los Angeles yesterday to wrap up the details of their DC10 probe. McDonnell Douglas builds the three-engine wide-body jet there, and most of the FAA's documents on the plane are in its western regional offices there.
Foster outlined generally the changes that will have to be made in DC10 maintenance or equipment:
A tough, high-frequency schedule of inspections will be required for the pylons that hold the wing engines on. In Chicago, the left wing's engine and pylon fell off just as the plane was lifting off the runway. Two of the three main attachment points had failed, investigators have discovered. New inspections will be timed to detect any problem in the pylon area before it can grow into catastrophic damage, Foster said.
A replacement schedule will be developed for control cables, with emphasis on those that control the salts, leading-edge lift devices on the wings. Those cables were served in the Chicago crash when the pylon left the wings, as were the hydraulic systems powering the salts. The left wing slats retracted while the right wing slats remained extended. This gave the right wing more lift, and the plane rolled to the left, stalled and crashed.
Dual electrical systems will be required on the stall warning and stick shaker, two devices that could have told the American Airlines pilot he had real trouble in time for him to do something about it. Only one electrical system was used on the American Airlines DC10 for the stall warning and stick shaker, and that system was knocked out when the engine fell off the wing. If a second electrical system was backing it up -- as is the case on some airlines' DC10s -- it is possible the pilot could have save the plane, aviation experts speculate. Once the plane rolled to the left, however, the pilot had no chance, the experts agree.
An inspection will be required of all control cables, slats and stall warning systems. Replacements, if needed, will be made. The stall warning will have to be wired in such a way that it senses the condition of the slats on both wings, not just one. A few planes may have to be rewired, FAA spokesman Jerome Doolittle said, but the time involved is believed minimal.
Each DC10 must successfully pass inspection before it can be returned to flight. Dual electrical systems on the stall warning and stick shaker will not be required before flights can resume, but will be required within a certain time. That schedule, plus schedules for re-inspection of the pylon, stall warning, control cables, etc., were among details unresolved last night.
Assuming no new problems turn up, FAA officials said, most DC10s should be able to fly shortly after their inspections are completed.
Last Friday, the FAA announced procedures for highly detailed and technical one-time inspections of all DC10 wing pylons as a prelude to recertifying the aircraft. One plane, a United Airlines DC10 in Newark, was discovered to have a small crack in a non-critical pylon area, Foster said. That pane was dispatched without passengers to San Franciso last night for more detailed inspection "so we can understand exactly what is involved," he said. No other problems have been reported as a result of the one-time inspections, Foster said.
The FAA will continue to study possible changes in procedures for DC10 pilots in the event of an engineout takeof, Foster said, but such changes will probably not be a prerequisite for restoring the plane to service.
Dozens of test flights in the DC10 simulator at McDonnell Douglas have shown, Foster said, that the plane could be flown with the engine off the wing if the pilot knew all the problems and operated the aircraft differently. As it was, experts agree, Capt. Walter Lux handled the controls exactly as he had been trained to do.
Foster said that the FAA regards the crash of Flight 191 as "a unique accident. It is hard to tell exactly what would have helped." It is clear, however, he said, that if the plyon had not fallen off the wing, other problems slats, hydraulics and electrical systems would not arisen.